You may not look at messages I/O statistics with Ultrapeers, simply because Ultrapeers is shielding the network to you, to avoid flooding you with unneeded messages.
What heppens is that your client sends a compressed hashed directory of your shared files, when it connects to the ultrapeer, so the ultrapeer will only send you those search requests that match the hashed version of your shared files. So you won't get large traffic from ultrapeer and this behavior is great to help reduce your bandwidth usage.
More, the Ultrapeer will avoid flooding your connection with many ping/pong messages because you the ultrapeer makes the connection work for you.
This is why you won't get many messages from ultrapeers, and a low traffic (about 0.3 to 0.5 KB/s) will be seen, instead of the previous traffic (3 to 7 KB/s) seen when connected to non ultrapeer nodes.
You can see that your connection is shielded by the fact that the hosts column displays "?" instead of the actual number of hosts. Don't worry about that. If your statistics window shows you about 500 hosts when connected to a single Ultrapeer, it's great and you have good connectivity to the network.

The statistics window will often reach an average count around 1000 hosts with 3 connections to ultrapeers, but this is just an estimate based on the unshielded messages that went to you from ultrapeers. In fact you have a much larger network connectivity for your searches, much more than if you only had connections with non-ultrapeer nodes.

In the next months, a protocol solution may be developed and tested so that each ultrapeer could accurately estimate their connectivity and report it to their leaf nodes. For now, the "?" display is normal, and all you need to look at is the global statistics window.

You'll benefit from more and faster results for your searches even if your traffic from Ultrapeers is apparently low: you'll notice a very temporary spike in the traffic from Ultrapeers ONLY when you actually perform a search with popular keywords, simply because you get nearly immediate results for your searches. This demonstrates that Ultrapeers have a good connectivity and manages the network efficiently.